Such a plug coupling with an additional locking element is known, for example, from WO 96/34224. The locking element is here designed as a catch which is attached in a manner so it can be pivoted via a hinge which is formed on the external surface of the coupling housing. A locking tongue is formed on the catch which, during engagement by pivoting of the catch after the engagement of the insertion part, is arranged between a slit trap which reaches into the housing, and the retaining rib in order to prevent the insertion part from being pulled out of the accommodating space of the coupling housing.
This locking element, in its constructive design, is unsatisfactory because it requires, for its attachment and to achieve the desired locking effect to the coupling housing, various constructive changes and adaptations. In addition, the manufacture of the hinge connection also requires an additional work step that increases the manufacturing cost of the entire plug coupling. Finally, it is considered a drawback that the catch prior to the pivoting projects transversely upward and thus occupies a large amount of space in the open position.
The object of the invention is to design the above described locking element for use with the existing plug coupling housing in such a manner that the modification of the plug coupling to add the locking element is possible with minimal constructive effort and without any changes to the coupling housing and so that the handling properties of the additionally applied locking element in the delivered state are not negatively affected.
This objective is substantially solved by the present invention which can be pressed without problem onto the head of the coupling housing in the axial direction and easily shifted into the locking position after the establishment of the coupling connection with the insertion part. In this process, it is ensured by means of the positioning humps on the internal side of the front wall that the locking element is secured both in its opening position and in its locking position. Additionally, the locking element can be used for retrofitting existing coupling housings without a great effort, even if the coupling housings are already in use.